A synovial sarcoma characterized by the presence of both an epithelial and a spindle cell component. The disease is Monarch Disease Ontology entry MONDO_0003468 (biphasic synovial sarcoma). Also known as: biphasic sarcoma of synovium, biphasic sarcoma of the synovium, synovial sarcoma, biphasic, synovial sarcoma, biphasic (morphologic abnormality).